Modern F1 hybrid varieties have all female flowers, do not require pollination, and should therefore not become bitter. It is only if you are growing open pollinated or ridge cucumber types which have male and female flowers that you should taken off the male flowers.
If this is a hybrid type and is still bitter, then it must be due to cultivation problems or poor growing conditions.

Are you giving them loads of water - at least twice a day in this heat - and a wateringcanful each time?

You don't remove male flowers from outdoor cucumbers.

F1 female hybrids do occasionally produce male flowers which can cause bitterness if not removed.

Thanks for your info Friends.
I'm growing them in the greenhouse, maybe I haven't given then enough water? I will get the all female ones next year LOL. Oh! Well, you learn by your mistakes LOL.
xx Jackie xx